Special Issue Information

Dear Colleagues,

A cyber-physical system (CPS) is a tightly coupled integration and coordination of computing elements, communication components, and physical resources. A multitude of wired and/or wireless communication/sensor networks connect these computing elements and physical resources. It is insufficient to study each of the following in isolation since a CPS is not their union, but their intersection: embedded computers, control theory, sensor and communication networks, physical resources, decision theory, data fusion, and knowledge discovery. Their joint dynamics must be studied together and this is what set this emerging discipline apart from these individually established fields. Before deploying a CPS, a formal modeling, analysis, and verification must be performed on the entire system, as well as its components, to ensure the CPS's safety, performance, and resilience. This Special Issue is devoted to the latest research in CPS and solicits papers in the following (but not limited to) topics:

Real-Time and Embedded Systems

Design Space Exploration and Synthesis

Control and Optimization

Automatic Optimization of Specifications and in Compilers, and Code Generators

Timing and Performance Analysis

Timing Analysis of Functional reactive systems

Model-based Testing

Correct-by-Construction

Requirements Modeling and Analysis

Model-driven Engineering

Application of Formal Methods in the design and validation of embedded systems

Safety Analysis

Fault Tolerance and Resilience

Sensor Networks

Code Generator Verification

Machine Learning

Data Fusion and Mining

Security

Dr. Albert M. K. ChengGuest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Abstract: This paper is about better engineering of cyber-physical systems (CPSs) through better models. Deterministic models have historically proven extremely useful and arguably form the kingpin of the industrial revolution and the digital and information technology revolutions. Key deterministic models that have proven successful include differential equations, synchronous digital logic and single-threaded imperative programs. Cyber-physical systems, however, combine these models in such a way that determinism is not preserved. Two projects show that deterministic CPS models with faithful physical realizations are possible and practical. The first project is PRET, which shows that the timing precision of synchronous digital logic can be practically made available at the software level of abstraction. The second project is Ptides (programming temporally-integrated distributed embedded systems), which shows that deterministic models for distributed cyber-physical systems have practical faithful realizations. These projects are existence proofs that deterministic CPS models are possible and practical.

Abstract: Research on wireless sensor networks has progressed rapidly over the last decade, and these technologies have been widely adopted for both industrial and domestic uses. Several operating systems have been developed, along with a multitude of network protocols for all layers of the communication stack. Industrial Wireless Sensor Network (WSN) systems must satisfy strict criteria and are typically more complex and larger in scale than domestic systems. Together with the non-deterministic behavior of network hardware in real settings, this greatly complicates the debugging and testing of WSN functionality. To facilitate the testing, validation, and debugging of large-scale WSN systems, we have developed a simulation framework that accurately reproduces the processes that occur inside real equipment, including both hardware- and software-induced delays. The core of the framework consists of a virtualized operating system and an emulated hardware platform that is integrated with the general purpose network simulator ns-3. Our framework enables the user to adjust the real code base as would be done in real deployments and also to test the boundary effects of different hardware components on the performance of distributed applications and protocols. Additionally we have developed a clock emulator with several different skew models and a component that handles sensory data feeds. The new framework should substantially shorten WSN application development cycles.

Abstract: In this paper, we present a system simulation framework for the design and performance evaluation of complex wireless cyber-physical systems. We describe the simulator architecture and the specific developments that are required to simulate cyber-physical systems relying on multi-channel, multihop mesh networks. We introduce realistic and efficient physical layer models and a system simulation methodology, which provides statistically significant performance evaluation results with low computational complexity. The capabilities of the proposed framework are illustrated in the example of WirelessHART, a centralized, real-time, multi-hop mesh network designed for industrial control and monitor applications.

Abstract: Regional heavy rainfall is usually caused by the influence of extreme weather conditions. Instant heavy rainfall often results in the flooding of rivers and the neighboring low-lying areas, which is responsible for a large number of casualties and considerable property loss. The existing precipitation forecast systems mostly focus on the analysis and forecast of large-scale areas but do not provide precise instant automatic monitoring and alert feedback for individual river areas and sections. Therefore, in this paper, we propose an easy method to automatically monitor the flood object of a specific area, based on the currently widely used remote cyber surveillance systems and image processing methods, in order to obtain instant flooding and waterlogging event feedback. The intrusion detection mode of these surveillance systems is used in this study, wherein a flood is considered a possible invasion object. Through the detection and verification of flood objects, automatic flood risk-level monitoring of specific individual river segments, as well as the automatic urban inundation detection, has become possible. The proposed method can better meet the practical needs of disaster prevention than the method of large-area forecasting. It also has several other advantages, such as flexibility in location selection, no requirement of a standard water-level ruler, and a relatively large field of view, when compared with the traditional water-level measurements using video screens. The results can offer prompt reference for appropriate disaster warning actions in small areas, making them more accurate and effective.

Planned Papers

The below list represents only planned manuscripts. Some of these
manuscripts have not been received by the Editorial Office yet. Papers
submitted to MDPI journals are subject to peer-review.

Type of Paper： ArticleTitle: Efficient Evaluation of Wireless Real-time Control NetworksAuthors: Peter Horvath, Mark Yampolskiy, Yuan Xue, Xenofon Koutsoukos and Janos SztipanovitsAffiliations: Vanderbilt University; E-Mail: Xenofon.Koutsoukos@vanderbilt.eduAbstract: In this paper, we present a system simulation framework for design and Performance evaluation of complex wireless cyber-physical systems. We describe the simulator architecture, and the specic developments that are required to simulate cyber-physical systems relying on multi-channel, multihop mesh networks. We introduce realistic and efficient physical layer models and a system simulation methodology which provides statistically significant performance evaluation results with low computational complexity. The capabilities of the proposed framework are illustrated on the example of WirelessHART, a centralized real-time multi-hop mesh network designed for industrial control and monitor applications.

Type of Paper: ReviewTitle: Optimization and Control of Cyber-Physical Vehicle SystemsAuthors: Justin M. Bradley and Ella M. AtkinsAffiliations: University of Michigan; E-Mail: ematkins@umich.eduAbstract: Cyber-Physical Systems (CPS) are composed of tightly-integrated computation, communication, and physical elements. Medical devices, buildings, mobile devices, robotics, transportation, and energy are application domains that can benefit from CPS co-design and optimization techniques. Cyber-physical vehicles are rapidly advancing due to progress in real-time computing, control, and artificial intelligence. Multidisciplinary/multi-objective design optimization enables vehicle systems to be designed to maximize efficiency, capability, and safety while online regulation enables the vehicle to be responsive to disturbances, modeling errors, and uncertainties. A CPS is cooperatively optimized or co-optimized over both cyber and physical systems which have historically been designed separately then integrated. A CPS is cooperatively regulated or co-regulated when cyber and physical resources are commanded in a manner that is responsive to both cyber and physical system properties. This paper will review research in CPS that focuses on co-optimization and co-regulation schemes for CPS with focus on mobile robotic and vehicle applications. Time-varying sampling patterns, sensor scheduling, anytime control, feedback scheduling, task scheduling, and resource sharing will be examined.

Type of Paper： Review Title: Cyber-Physical Systems: A Fundamental Intellectual Challenge Authors: Edward A. Lee Affiliations: University of California at Berkeley; E-Mail: eal@eecs.berkeley.eduAbstract: The term cyber-physical systems (CPS) refers to the integration of computation and networking with physical processes, where sensors and actuators act as gateways between the cyber world of information technology and the physical world. Although many of the elements of CPS are familiar and not altogether new, as an intellectual subject, CPS is pushing hard at the frontiers of engineering methods, putting severe stress on the abstractions and techniques that have proven so effective in separated cyber and physical worlds. Notions of time and dynamics (the evolution of the state of a system in time) differ in these two worlds, and the engineering abstractions that we have built to cope with them do not mesh very well. While the engineering abstractions used in separated cyber and physical spaces are key enablers of the high-tech revolution of the 20th century, when they are brought together, key properties of these abstractions break down. For example, in the semantics of all widely used programming languages, the physical time that it takes to perform any action is irrelevant to the correctness of the execution of the program. Only the sequence of actions matters, a key property of all algorithmic cyber-world abstractions. But when these actions affect the physical world, the time at which they are performed matters. Lacking good abstractions that mesh key properties of these two worlds, engineering practice today is forced into a prototype-and-test style of design. This paper explains how we can do better.